While much of the country rallied behind the crew's return, others criticized them for offering apologies where none was required - namely for appearing in videos in which they admitted and offered regrets for entering Iranian waters.
Defense officials sought to quash the criticism and said that none of the sailors and marines will be punished for making the apologies.
Prime Minister Tony Blair was somber. He said that while the country celebrated the safe return - and praised the diplomacy that secured their release - the joy was diminished by the killing of four British soldiers in Iraq on Thursday.
"Just as we rejoice at the return of our 15 service personnel, so today we are also grieving and mourning for the loss of our soldiers in Basra, who were killed as the result of a terrorist act," Blair said outside his office at 10 Downing St.
Iran's release of the eight sailors and seven marines raised hopes among some that Tehran might be open to compromise on other matters, particularly Western demands for a halt to Iran's uranium enrichment program.
But Iran already was warning it would retaliate if the West pushed too hard, and U.S. officials intensified their criticism of Tehran after restraining their comments during the 13-day standoff over the British naval crew.
Gordon Johndroe, spokesman for the National Security Council, said Washington saw no sign of Iranian willingness to work with other nations on scaling back its nuclear program, which the U.S. and its allies suspect is aimed at producing atomic weapons.
"What would show that they're more in line with the international community is to comply with the U.N. Security Council resolution" calling for a freeze in the Iranian nuclear program, he said.
The freed crew left Iran Thursday morning, traveling in business class on a British Airways jetliner with staff from the British Embassy in Tehran. Flight attendants passed around champagne as a Royal Navy officer reminded the former prisoners they were on duty.
Filing off the plane at London's Heathrow Airport after a 6Â½-hour flight, the team members carried blue and orange duffel bags and shopping bags, some apparently holding candy and souvenir gifts from Iranians.
They spent a few minutes on the tarmac, smiling and standing at attention - dressed in crisp blue naval and brown camouflage marine uniforms rather than the ill-fitting civilian clothes that Iranian officials provided for their release.
Then two Sea King helicopters ferried the crew 210 miles to the Royal Marine base at Chivenor for a reunion with families. As they hugged relatives, TV cameras caught Leading Seaman Faye Turney - the only woman among the captives - wiping tears from the corner of her eye.
A lunch with families followed at the base cafeteria. They were described by the military as "in good spirits."
The crew was expected to remain at the base at least until Friday for debriefing about their seizure by Iran, which charged the naval team intruded into its waters in two inflatable boats. Britain insisted the crew was searching for smuggling on Iraq's side of the Shatt al-Arab, a disputed waterway dividing Iraq and Iran.
Britain's Sky News reported that an officer in the captured crew, Royal Marine Capt. Chris Air, had said in an interview three weeks ago that the team gathered intelligence on Iran during its patrols.
The Defense Ministry denied the team had any special intelligence role. It said they routinely spoke to commanders of vessels using the Persian Gulf and Shatt Al-Arab to determine who is using shipping routes. British Broadcasting Corp. reported that the Iranians kept one of the crew members in solitary confinement. The BBC did not identify the person, but said the information came from the family of one of the sailors. A military spokesman, Lt. Col. Andy Price, later said some of the personnel had been "left alone" at points during their captivity, but declined to elaborate until officials talked more with the team members. Although several sailors appeared on Iranian state television, others were not filmed - raising the possibility they may have been separated from colleagues. Several of the crew praised their treatment in interviews with Iranian broadcasters, but in a joint statement released as they arrived in Britain, the sailors and marines said that "the past two weeks have been very difficult." "By staying together as a team we kept our spirits up, drawing great comfort from the knowledge that our loved ones would be waiting for us on our return," the statement said. Videotape of the crew apologizing for entering Iranian waters, and letters purportedly written by Turney were widely publicized, and some British newspapers reacted with dismay. The tabloid Sun wrote that "nobody emerges from this crisis with credit." "The sight of the illegally detained British forces thanking Iranian tyrants for their freedom will sicken the nation," said the tabloid's editorial. Daily Mail columnist Stephen Glover said he didn't blame the crew for thanking Iran's hardline president, Mahmoud Ahmadinejad, or for their confessions. But he said the overall impact would be clear. "However much they may retract their statements when they return to safety, and whatever further â€˜proof' the British Government may choose to produce, our enemies and detractors will believe we have been humiliated, and rejoice in that fact," he wrote. But Air Chief Marshal Sir Jock Stirrup, the chief of the defense staff, dismissed questions about the crew's conduct during captivity. "They did exactly as they should have done from start to finish and we are proud of them," he said. Stirrup also reiterated the British position that the naval team was operating in Iraqi waters when it was seized. "We are absolutely clear the incident took place on the Iraqi side. We are going to have a discussion with the Iranians to ensure that we do not get into this situation again," he said. Wednesday's surprise announcement by Iran's president that the Britons had been released was a breakthrough in a crisis that pushed oil prices to six-month highs and escalated fears of military conflict. Iran let the team go without the main thing it sought - a public apology from Britain - suggesting Iranian leaders did not want to push the standoff too far. A day after the naval team was seized, the U.N. Security Council imposed more sanctions on Iran for refusing to halt uranium enrichment and the team's capture drew widespread criticism. A senior British government official said international support helped break the deadlock. Countries ranging from Syria to Colombia pressed Iran for the release of the crew, whose capture began at the start of the two-week Iranian new year celebrations. "By the time the senior Iranian leaders were getting back from their holiday, they were finding that their phone was ringing off the hook and they were finding that an awful lot of countries - including some quarters they weren't expecting - were ringing them and saying they were in the wrong place and they should be releasing the people quickly," the official said, on condition of anonymity because of the sensitivity of the situation.